Is it a Falsehood that Humans Evolve from Apes?
How about this one: Is it a Falsehood that Humans did NOT evolve from Apes????
Yes and no. Humans descend from a population of primates from which other apes also descended (minimally the two species of living chimps) and which was part of the panoply of late Miocene forms, all related to each other, that we call apes. So yes, humans evolved from apes.
There are people who don't believe that. They, creationists, think that apes are apes and humans came from somewhere else, like the Garden of Eden or Mud or whatever. (This may depend on which flavor of creationist and, frankly, which humans the creationist is talking about ... by some creationist theories, white people came from Eden, while various brown people came from various mud, and Jews came from monkeys.) When creationists object to the phrase "Humans evolved from apes" evolutionary biologists tend to respond with a long list of reasons that we should assume that humans and chimps DID evolve from a common ancestor which was an ape of some kind.
People who are not creationists, but still prefer some kind of human exceptionalism, may not like the phrase because it strongly implies that humans are apes, and they may prefer that we be thought of as different from apes.
Either way, we need to understand that the phrase "Humans evolved from apes" has two distinct meanings for people who hear it. One emphasizes the word "apes" and the other emphasizes the word "from." By one way of thinking, the phrase means "Homo sapiens is one of several species of ape." By the other way of thinking, the phrase means "Homo sapiens evolved from apes into something different." Either way, some people will be annoyed. Either way, the statement may be correct.
When science educators, hear resistance to a phrase linking humans to apes, we tend to want to push the humans back in with the apes right away. We don't want to encourage any sort of human exceptionalism, or any sort of random nonsense about how evolution didn't happen. And, a natural extension to that way of thinking is to insist that humans are apes. Fully, unexceptionally, undeniably, apes.
Putting this in a slightly different, perhaps demented matter: "Humans evolved from apes" is wrong because "Humans evolved from apes."
Remember the point of falsehoods: They are statements that are typically associated with meanings or implications that are misleading or incorrect, and in some cases downright damaging. "Humans evolved from apes" is an excellent example of a falsehood because it is technically correct, yet the implied meanings that arise from it are potentially wrong. Even more importantly, you can't really analyze the statement "Humans evolved from apes" without getting into an extended discussion of what an ape is and what a human is. And this is a trick one: The reason "humans evolved from apes" is false has nothing to do with the fact that it is true (which it is). It has to do with what is going on in people's minds when they think "humans" (or "apes" or "evolved" or "from").
So, how true is the statement that "humans ARE apes?" Humans are apes phylogenetically, but then again, apes are mammals phylogenetically and to say "apes are mammals" is trivial and uninteresting. It may be that there are interesting and important things about apes that make them apes to the exclusion of aardvarks or some other mammal. For example, if you go with the "apes are apes" idea, then apes are monogamous, 7 to 16 kg in body mass, eat almost exclusively fruit, and locomote almost exclusively by hanging under branches. The fact that this description excludes gorillas, chimps, and bonobos is of little consequence, because the vast majority of ape species are gibbons and siamangs.
"But wait!" you say, "Chimps and gorillas are great apes! When we say 'apes' we mean great apes! They are different than the broader category of apes!"
OK, fine, I'll buy that, but you must now understand that you've fallen into my little trap! If great apes are distinct from "the apes" and you want to call them something different because of their body size, their locomotary pattern, their diet, and their mating system, then the same exact argument can be applied to humans, and humans are arguably not "apes" but some other category. Humans do not eat exclusively fruit (they eat mainly grains, roots, fruits, meat); they are similar to the great apes in body size, but not in body size dimorphism. They locomote in an entirely different way, and they have an entirely different mating system. And there are other differences as well.
So, the "from" in "humans evolved from apes" is OK if we want to think of humans as different from apes. Or, if you don't like that you could say "humans are a form of ape" ... (I often mistype from as form and form as from, so to me, it makes little difference!) ... I'm not going to tell you that either one is wrong, because I'm agnostic on that point.
However, I tend towards thinking of humans as apes simply because of the pedagogical (and damaging) importance of human exceptionalism. Better that we think of ourselves as a form of ape. Well, actually, better that we think of ourselves as highly inadequate bacteria. But THAT is a different story altogether....
As an experiment in both thinking about this and pedagogy, I've written part of the above discussion in a different way. Have a look:
The Kladistic Konundrum ...
Cladists like to point out that a monophyletic (all related to each other and not distributed across a set of evolutionary branches with extra twigs in there) group is a member of the larger monophyletic group to which it blongs. Thus, a human is an ape, an ape is a primate, a primate is a mammal, and so on and so forth. Therefore, plain and simple, "humans are apes." Anything that looks or smells like a contradiction to that is necessarily wrong.
This "cladistic requirement" is true, but it is sometimes misapplied. This is because a perfectly good monophyletic group can be joined with, or even infiltrated by, a perfectly good alternative category that is actually meaningful. For instance, it appears based on recent genetic research that polar bears are a form of brown bears. There is one species of brown bear seen as numerous populations including the Kodiak bear, the grizzly bear, the European brown bear, etc. Within this clade, as a branch not adjoining the brown bears but within them, is one population that happens to be maritime adapted and white. The polar bear. So, we have a separate species sitting there within a clump of closely related populations.
Does this mean that the numerous derived adaptations seen in polar bears are less important than they otherwise might seem, and the polar bear is just a subspecies of brown bear? Or, does it mean that there are several species of brown bear, rather than several populations, and one of them is white and eats seals? Yes, both could be true, depending on what you think is important. It think, though, that most people would keep the brown bears as one species and the polar bears as another species, and simply admit, despite the cladistic requirement, that a new "kind" of bear has emerged from another. Perhaps some day there will be multiple species of polar bear descending from this current form.
The following little conundrum illustrates the triviality (and misleading nature of) the cladistic requirement in relation to the question at hand (humans evolving from apes, or not).
When most people say "humans are apes" they do not mean that humans are "small bodied almost exclusively arboreal fruit-eating suspensory monogamous primates" which is what the vast majority of apes are, given that this describes gibbons and siamangs, and most apes are gibbons and siamangs.
Yes, it is true that apes can be divided into lesser apes and great apes. The lesser apes diversified first, the great apes later. So, why are the great apes not just a form of lesser apes? If your claim that humans "are" apes because they (hominids) diversified from an ape population is valid, then that logic MUST be applied to the other apes, so great apes are lesser apes.
Therefore, when a person says "humans are apes" they mean that humans are "small bodied almost exclusively arboreal fruit suspensory eating monogamous primates. Which they're not. And, have they realized they were saying that, they probably would have put it differently.
Note: Other blog posts in the Falsehoods II series can be found here. The current falsehood is part of this installment of "Everything you know is sort of wrong" on Skeptically Speaking radio.
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No, most apes are human.
What a long-winded blog about nothing. Who cares what creationists think - if they're even capable of thinking? Ape is a set & human is a subset. Humans are apes that evolved from other apes. Humans are apes, are mammals, are highly derived sarcopterygian fish, are Terran life forms. What's so difficult about simple set theory to understand? You must be awfully bored, Greg, to go to all this trouble over such trivialities.
OK. I had the hardest time to understand your point, since it was arguing against conflating models by accepting the conflations and arguing from them. I'm not a biologist, but I don't see how having different models can be a problem.
Unless you conflate which creates confusion, and a good example of that is made under the heading The Cladistic Conundrum. I take it that cladistics use the map of a branching tree like an idealized phylogenetic tree can be. (Say, by artificially replace diverging populations with pair-wise branching: i.e. \/, not \|/ or \ \/ /.) Then the map of nestings would be nested subsets.
I.e. here polar bears would be a proper subset of brown bears, while brown bears would not be a proper subset of polar bears. Yet the discussion tries to make them out differently than mere sets, which is a conflation: "several species of brown bear, rather than several populations, and one of them is white and eats seals?"
But it is clear that for a cladist a polar bear is simply both a polar bear and a brown bear. Simple enough, I guess, and perhaps too simple to press biological species onto the mapping seeing the discussion. But what weight the traits have, or if the populations actually form biological species, is presumably not relevant for the application of that model.
Who cares what creationists think? Well, teachers with creationist students, for one example. If you don't know what kind of preconceptions your students start with, and how what you say will resonate with those preconceptions, you're not going to get very far in teaching them.
I take it that Laden means Obfuscator in your native tongue.
I taught biology for many years Stephanie, from the middle school to university level, and I never really cared what preconceptions my students had. I presented them with the facts, as I understood them, and what they did with the information was up to them. If students could demonstrate that they understood the facts they got the grade. I didn't care if they "believed" those facts were true or not.
No, most apes are human.
Darwinsdog, It should be obvious that I mean most ape species. Neurons, boy. Try using them. And, start being a bit more polite or you're outta here.
Torbjörn Larsson:
I.e. here polar bears would be a proper subset of brown bears, while brown bears would not be a proper subset of polar bears.
That is not the point. Polar bears, by their existence, ruin the monophyly of brown bears. The equivalent with apes wold be us having put gorillas and both species of chimps into one highly variable species. Since humans emerge from within that branch of the family tree, the humans break the monophyly of the apes.
This is not really a problem about sets (though that is part of it). It is a problem of how intermediate classifications work (between species and instances of live itself evolving, for which we at the moment assume there is one related to this discussion).
Remember the point of the falsehood discussion.
I taught biology for many years Stephanie, from the middle school to university level, and I never really cared what preconceptions my students had.
Seriously? You must have sucked as a teacher. No wonder you go without using your real name! Wow.
Anyway, for better or worse, this entire discussion is predicated on the idea that understanding misconceptions is fundamental to good teaching. This (good teaching) may be something you are .. unfamiliar with, or perhaps disdain. (At the moment, I'll assume that you are making all this up because no one could actually be you and have done what you've claimed!)
Hypocrite.
Yes it is. Circles within circles. Humans within apes within primates within mammals... In fact, that's all it's about. Trivial.
Okay, go ahead & thrash. I'm done with this nonsense.
I totally get this. There is not a meaningful break between, for example, some sparrow and sparrows in general, but there is a meaningful break between polar bears and brown bears. A simple minded "set theory" approach ignores those meaningful breaks. Excellent.
Is that Darwinsdog the gun nut?
Confirmed: darwinsdog does not get it.
Greg said:
"Humans are apes phylogenetically, but then again, apes are mammals phylogenetically and to say "apes are mammals" is trivial and uninteresting."
I would dispute the claim that it is trivial and uninteresting. If it were so, then the entire discussion following shares that quality (hopefully you were speaking tongue in cheek, though it seems Darwinsdog shares that sentiment :))
The problem is the embedding of older classification schemas into newer practices. With the Linnean split of Pongo and Homo we ignore the stong phylogenetic similarities which likely tie the two taxa together as a single genus that is likely evident in a claudogram.
My method for teaching these distinctions was to employ Eohippus to show the horse lineage, getting my students all comfortable with that monophylly, and then I'd pull the same thing with Eohippus being the ancestor of the tapirs. After that, addressing the loaded question of humans from apes was made much clearer.
Mike
Mike: It is a trivial and uninteresting thing to say about apes. The mammalian context is important (and nontrivial and interesting) but that is clearly not what I was talking about.
If you want to make the case that a newly discovered species is an ape, proving that it is a mammal is not going to help (non trivially).
The tapir gambit is a good one.
Great blog! I think the trouble with this kind of non-falsehood is that the subtleties are lost on those that need to understand it the most...'those' being creationists and evolution skeptics.
It's this approach that scientists cheer because of its accuracy, depth and thought. But, its what creationists jump onto to call vague and circular.
So - I ask you - how can we say, concisely and accurately, to someone who doesn't believe in evolution the 'quotable' from this article? Without losing the subtlety?
Is "Humans evolved from apes" still sufficient?
Woirmgirl:
It is helpful to take time out of the equation initially, and then add it back in only when there is some mutual understanding of time, diversification, and evolutionary relationships.
The discussion above, some of it rather pissy in nature for unknown reasons, about "sets" belies the reason for this. "Sets" only works as an approximation. It is worse than plain cladistics (which assumes "pairs" always, almost always true, at least, while these "sets" are false post hoc constructions). So, yeah, the diachronic aspects are being lost in this discussion.
So, I would say "Humans and other apes are members of the same taxon.
[The taxon is the Hominoidea (or the Hominoids) (or, if you prefer, some other term or taxonomic level depending on your point)]
The following are also helpful. Never refer to the apes or the primates as distinct from humans without using the affix: "Non-human." Like using "other" in the above sentence. One could say:
Humans and non-human apes are members of the same taxon, the hominoids.
(But the first way sounds better, both mean the same thing.)
No. Humans are not "apes phylogenetically". Humans are Hominoidea phylogenetically.
Again: "Apes" is not a phylogenetic term or concept. The apes are some non human members of Hominoidea.
For the same reason we descended from fish, but we are not fish. We descended from invertebrates, but we are not invertebrates. We descended from microbes, but we are not microbes. Etc. Microbes, fish, invertebrates, etc., are not valid phylogenetic "cladistic" groups.
Hominoidea = The Apes: this is the real falsehood :o)
El, maybe. Maybe not. The fact that "ape" is a common term allows us to put at least one monkey in the "ape" category because it is called an ape. But not everyone accepts that the hominoidea = humans + non-human apes. (Ooops, there we go again with the use of the word ape.) Some people do, some people don't. As I stated, I'm agnostic on the question.
But there is a pretty good chance that you will be accused of human exceptionalism in three... two... one....
feh.
We're the hairless ones with the particle accelerators who generally peel bananas from the wrong end.
"But not everyone accepts that the hominoidea = humans + non-human apes"
Hominoidea also includes lots of species that are nor human nor apes. Australopithecines for example. Sort of ape-men. Yes, evolution happens! :o)
"But there is a pretty good chance that you will be accused of human exceptionalism"
I supponse I am also an ant-excepcionalist because I think an ant is not a wasp. I was accused of creationism too (when I was defending taxonomic nomenclature accuracy *and* evolutionary transformation). I don't mind...
It is my view that australopiths are not not apes.
Not not?
Please clarify if that's intentional.
El Paleo explicitly stated that Australopiths are neither ape nor human. I am disagreeing.
I would be interested to know why you think australopiths are not apes, although I guess it is consistent with the view that humans are "not apes".
Here's a question - how would a blogger Chimpanzee approach the issue?
Sorry, I missed the "not not" but my mind is now spinning through triple negatives and perhaps quadruple negatives, or into a painting by Magritte ("this is not a pipe"), or into the "All Greeks are liars" paradox, or something. On the other hand I have the flu, so maybe I am hallucinating.
Australopiths are either ape or human, according to creationists.
But they are neither. They are transitional forms, with mosaic and intermediate features of apes and humans. Their transitional structure was a GREAT discovery, a real scientific milestone.
I took anthropology from a man who was a primatologist by training. I saw nothing wrong with this. Clearly men are primates, and so the study of man is clearly a subset of the study of primates.
In any case, this fellow insisted that the most important way to separate out your primates was by locomotion. Humans are unique in locomotion (to say nothing of the generally underutilised potential of our massive brains) among living animals, thus necessarily granting them a separate category.
And there's real value to that. Simply walking upright gives humans a greater kinship in function (or at least dysfunction) and experience to our fallen bipedal cousins than to our living knuckle- and palm-walking cousins.
Any idiot can tell you a bird isn't a dinosaur, nor a man a fish, nor a polar bear a brown bear.I think it's high time we stopped confusing people by trying to use morphological terms to label clades.
But a bir *is* a dinosaur: a member of the clade Dinosauria.
But that's what I was talking about: "Dinosaur" isn't properly the name of a clade, but of a pre-phylogenic taxon defined based on morphology from which all birds differ.
Appropriating a well-defined and broadly used morphological name (such as Dinosaur or Fish) to describe a clade simply serves to confuse the matter.
Are birds and dinosaurs different in any meaningful ways, El PaleoFreak?
"Dinosaur" is a scientific term coined by a scientist, used first in the science field, then spreading in the common language.
Dinosauria (which means "The dinosaurs") is also the name of a clade that include birds. Some commonly used definitions of Dinosauria even include birds by... definition.
"Humans are unique in locomotion" - all animals are "unique" in locomotion.
David: Yup. Humans are just another unique species.
But nope, it should be obvious to the well intentioned reader that I was referring to humans in relation to apes (that is what this discussion is about).
And, nope, "all animals are unique in locomotion" is not true. Many manmals, for instance, are members of taxa where all the species have the same exact locomotion to the extent that looking ony at the leg bones, experts can't tell them apart, or if they can, must rely on rather esoteric traits.
Hi Greg - I didn't mean "every species is unique in locomotion". I was disagreeing with the proposition of H.sapiens exceptionalism, that somehow our particular style of locomotion, among all the thousands (hundreds of thousands?) of styles that have evolved, makes us a uniquely attributed (you know what I mean) animal.
Human locomotion (modern humans) is actually pretty darn unique. Bipedalism sensu lato is not so unique .... most birds are bipedal, for instance. But this particular thing humans do is unique.
It is not necessary in our efforts to avoid human exceptionaism to ignore human exceptions. There is a reason that Foley named his book "humans, another unique species"!
It is helpful, when teaching about human evolution, to balance the non-exceptional parts with the exceptional parts at about a 3:1 ratio.
Hi Greg, we are talking at cross-purposes I think. The rest of the quote I was referring to above is "Humans are unique in locomotion (to say nothing of the generally underutilised potential of our massive brains) among living animals, thus necessarily granting them a separate category." The poster is wanting to support "necessarily granting them a separate category" not just, say, among apes, but "among living animals". Not too far from a separate creation there, I think, or at least an evolutionary diagram which is drawn as a pyramid with humans standing on the pointy top.
When this kind of thing is said, it is genuinely believed, I think, that ONLY humans have unique qualities, that every part of our body is at the top of a pyramid of perfection. I was trying to suggest that being "unique in locomotion" is no more (and no less) a reason for human exceptionalism, than having the locomotion style of a snake, a snail, an eagle, a horse, a whale, a mole, a penguin, a frog, a kangaroo, an earthworm, an amoeba and so on. This idea of "unique human beings" keeps coming up in every discussion of apes and evolution, and I had one go at it here in a different context http://davidhortonsblog.com/2008/08/14/i-see-dead-people/.
Ouch. Yes, I hadn't read that comment carefully.
Interesting that it includes the "we don't use much of our brain" myth.
Greg, I'm not at all an expert on either primate phylogeny or science education, but it doesn't seem to me that you've really identified any serious problems with saying "Humans are apes"--in either a phenetic or a cladistic sense (And I don't even like phenetics.)
"Vast majority" in this case is "about two thirds," no? I don't think most phenetics defenders would favor a definition that excludes a third of the species in the group you're talking about--including, of course, the one that's orders of magnitude more numerous than all the other species put together. And most lay Westerners certainly wouldn't accept a definition that leaves out the "classic" apes like gorillas and chimps; for that matter, I'm not sure most lay Westerners even know gibbons are apes and not just weird monkeys.
Why not say "apes are 7 to 200 kg in body mass, eat significant amounts of fruit, and share a shoulder girdle anatomy which allows them to locomote by hanging under branchesâ¦weight permitting?" You could throw in that they're tailless, have opposable thumbs and flat faces and broad chests and Y-5 dental patterns, and so on. This would cover 100% of known ape species, so far as I can see, while excluding all the most closely-related monkeys. And it would include humans.
I'm not sure anyone would respond to you in quite that way, though. They'd say, rather, that great apes and lesser apes are distinct, and so you shouldn't be defining "the apes" based on characteristics peculiar to one subgroup or the other.
But again, this just suggests to me that exclusive fruit-eating, body size dimorphism, locomotion and mating systems aren't good things to define "great ape" around in the first place. And really, they aren't anyway, are they? Great apes vary dramatically on all those fronts even if you don't include humans.
On cladistics:
Maybe I'm just ign'ant, but I have to disagree with all your premises here. My understanding is that:
a) Living apes can be divided into lesser apes and great apes. That wouldn't be true for all extinct apes.
b) Great apes did not diversify from a population of lesser apes. The two groups (Hominoidea and Hylobatidae) are sister taxa; they both diversified from some ancestral population of apes who were neither great nor lesser.
c) Lesser apes did not even diversify significantly earlier than great apes. The molecular divergence dates for both groups are "early Miocene-ish," and lesser apes actually show up later in the fossil record. (The latter fact doesn't tell you much, granted, since I'm sure gibbons fossilize even more rarely than great apes do.) Not that temporal priority matters to cladistic classifications anyway.
Given all that, there's no cladistic problem here. Humans are great apes, humans are apes, great apes are apes, lesser apes are apes, but great apes are not lesser apes.
I agree that "brown bear," just like "fish," might never end up having a workable cladistic definition, but I don't see that "great ape," "lesser ape" or "ape" is in the same boat.
Anton, I'm not arguing that we should not say that humans are apes. I am, however, not overly happy with what most people are actually thinking when they think any one of the four terms the post started with. And, there are in fact different valid opinions on the matter, some of which I like, some I'm agnostic on, some I don't like.
Given all that, there's no cladistic problem here. Humans are great apes, humans are apes, great apes are apes, lesser apes are apes, but great apes are not lesser apes.
Yes. There has never been a problem with the phylogeny. More accurately, humans and chimps are of the tribe Panina.
Here's the podcast:
http://www.skepticallyspeaking.com/episodes/65-transhumanism
JediBear,
What morphological features in particular?
I was doing some thinking on these lines and ultimately realised that the problem is that we're using the wrong verb to describe clades. Clades, of course, are groups characterised by common descent, and not by common features, so it's frankly silly to say that all the members of a clade "are" anything, and rather more sensible to say that all the members of a clade "descend from" or "evolved from" something. Thus, humans evolved from apes. Apes evolved from apes. All very clean and very sensible. Unlike referring to the lot of them as aberrant fish.
Yes, "dinosaur" is a scientific term, but one originally used to describe a morphologically-similar set of extinct animals known only from their fossilized remains. Despite the clear line of descent, it's simply wrong to say that birds belong in this group -- they actually have few common features, having quite moved on. Saying a bird is a dinosaur is little different from saying a bird is a fish. Both are wrong and both are, in modern cladistic terminology, absolutely correct.
"What morphological features in particular?"
Birds are universally small while dinosaurs, especially in the original conception of the term, are generally large (this is why, in fact, they are called dinosaurs -- the name was meant to evoke, as it does to this day, saurian creatures of tremendous size and power) Birds (with some exceptions) fly, other dinosaurs (without exception) do not. Dinosaurs generally have teeth and large, flexible tails. Birds do not.
Set an unfamiliar (nonbird) dinosaur side by side with an unfamiliar bird, and I will wager I can tell the difference without even inspecting them closely, whether they are presented only in skeleton (though I will have to insist on a full skeleton -- I'm no paleontologist) form or in life with full scales and feathers.
But Dinosaurs aren't even the best example.
Reptiles (by definition) are cold-blooded and scaly.
Mammals (by definition) are warm-blooded and hairy.
And yet Mammals are phylogenically Reptiles, and thus we reach a contradiction. It is impossible to define the terms "Reptile" and "Mammal" so that they are both morphologically consistent and cladistically valid.
Worse, we've been telling kids for a great many years that cetaceans are not fish, and yet it is impossible to construct a cladistically-proper class that includes all fish and yet excludes whales (or humans, for that matter.) Are humans fish?
No, but humans evolved from fish, by way of reptiles, mammals, primates and, most recently, apes.
Exactly. That is exactly why I suggest the phrase "Humans, Chimps and Gorillas are all members of the same taxon."
Note no adaptive or even diachronic terminology.
"Despite the clear line of descent, it's simply wrong to say that birds belong in this group"
Sorry, but it's simply *right*. Vertebrate paleontologists, dinosaur experts agree that birds are perfects members of Dinosauria. You'll find that in almost every paper about dinosaur phylogeny or bird origins. In today's taxonomy, birds are dinosaurs in the same way bats are mammals.
The apes thing is different. In this case some people are misaplying phylogenetic taxonomy rules.
There is still a falsehood there. Why should we call birds dinosaurs? No reason to at all. If I want to build a bird cage, I do not call it a dinosaur cage. The terms "bird" and "Aves" are proper useful terms that do not go away when it is realized that Aves is part of the same group that holds (most of the things called) dinosaurs. There is no conflict there. Birds are birds, and it's OK to call them birds, but birds are part of the larger clade called Dinosauria
What is a bit tricker is when we do it the other way. "Dinosauria" can't exclude birds. However, if I want to build a "dinosaur cage" (note the use of the common term "dinosaur" I'll make it to hold dinosaurs to the exclusion of birds.
Dinosaurs (non diachroincally speaking) exist to the exclusion of birds functionally, if not cladisitcally.
This is a fact that most cladist can't handle or understand. But it really is true.
The LCA of all living things had one cell. All living things are that LCA's clade. But there are many living things that do not have one cell.
How many cells an organism have ... is important in building cages for them! It is important for talking about them, identifying them, and at a pragmatic level, even classifying them.
A brown bear is NOT a polar bear.
"More accurately, humans and chimps are of the tribe Panina"
??
JediBear,
This seems flatly wrong to me. Birds share a host of common features with dinosaurs, as they do with archosaurs, as they do with reptiles in general. Skeletal anatomy, scales, feathers, egg-laying patterns, even behaviors like nesting and parental care and gastrolith use and vocal communication. "A theropod dinosaur specialized for flight" is a near-perfect definition of a bird.
Now, do birds have much in common with dinosaurs as they were originally characterized? Nope. But the people who originally characterized dinosaurs didn't know very much about them. I mean, if we were still defining dinosaurs around the features Owen thought they had, we'd have to say that dinosaurs are entirely mythical--because his semi-mammalian, obligately quadrupedal, massive-forelegged reconstructions don't resemble any dinosaur that ever actually existed.
"Dinosaur," like any scientific label, is an attempt to carve nature at its joints. If the joints turn out not to be exactly where we thought they were, there's absolutely nothing wrong with updating the definition to match. The evolution of the term "dinosaur" from the 19th to the 21st century reflects genuine progress in our understanding of the critters. In my non-expert opinion, anyway.
But "generally large" and "universally small" (where "small" includes, I assume, "ostrich-sized") are not incompatible. Mammals are generally small (most species being bats, rodents or insectivores) and elephants are universally large, but that doesn't mean elephants aren't mammals. They're just big mammals.
Yes, dinosaurs include creatures of tremendous size and power, but--in the age of Jurassic Park and The Land Before Time--even laypeople are comfortable with the notion that they're not all like that. Even if you leave out all the not-quite-birds like Archaeopteryx and Microraptor, there are well-known card-carrying dinosaurs like Compsognathus and Velociraptor that fall well within the size range of modern birds. And Velociraptor's feathered and (moderately) warm-blooded to boot.
Well, "without exception" only if you define all the dinosaurs with powered flight as birdsâ¦.in which case, it's no longer true that birds don't have teeth or large, flexible tails.
More importantly, even a truly unique feature of one group doesn't preclude it from being included in a larger group. Bats fly--without exception, at least among modern species. Other mammals, without exception, do not. That doesn't mean that bats aren't mammals, it just means that bats are flying mammals, and that flight isn't a good criterion for classifying creatures as "mammal" or "non-mammal" in the first place.
Forgive my skepticism, but many paleontologists have spent years wrangling over whether this or that maniraptoran dinosaur is a bird or a non-bird. I honestly don't think you could tell the difference in many of those cases...no one can. (Which is not at all surprising from an evolutionary viewpoint, of course.)
That doesn't actually follow. If you define them cladistically, they're still morphologically consistent--it's not like Reptilia/Sauropsida doesn't have any synapomorphies! You just can't use "cold-blooded vs. warm-blooded" as the morphological distinction. Not that you could anyway, if you wanted all dinosaurs to be reptiles.
Oh yes, "fish" is totally cladistically unsalvageable. A monophyletic "fish" would either have to include bears and parrots and toads and iguanas, or exclude sharks and lampreys and stingrays and coelacanths and lungfish, both of which options take you way, way outside any normal meaning of the word. But that's quite a bit worse than just having to throw birds into "dinosaur" or "reptile," IMO.
I like this "carving nature at its joints" metaphor.
For example, if you go with the "apes are apes" idea, then apes are monogamous, 7 to 16 kg in body mass, eat almost exclusively fruit, and locomote almost exclusively by hanging under branches.
Just one mostly off topic thing to add. As far as I'm aware, gibbons and siamangs are fully bipedal and spend a surprising amount of time on two feet, although they don't run in a fully upright position or extend the leg at the knee like humans do. When moving quickly through the canopy, they seamlessly switch between swinging leaps and quick sprints along larger, mostly horizontal branches. The internet is letting me down right now, in that I can't find a single example of this, but I have found something close with this video of some little prick harassing a dog.
http://www.youtube.com/watch?v=DoQwOVAN2kk&feature=related
Which is Better: Apes or Dogs?
Let me amend that to say âfully bipedal when not swingingâ before I'm called out.
Correct. And, funnily enough, the gibbon bipedality (which is evident when they are forced to walk on the ground for a period of time) is not directly connected to Hominid bipedality, yet "humans as apes" where apes mean all apes, would put this bipedal label on the humans by accident.
I didn't originate it, I hasten to say! Apparently Plato did--he puts it in Socrates' mouth, but that usually means he just made it up--in the Phaedrus.
Oh, yes. Most people are either thinking "My grandfather wasn't no chimpanzee!" or "My grandfather was a chimpanzee, I saw it in a movie!", neither of which is particularly helpful.
Speaking of bipedal hylobatids... I've read a lot of times that they *never* knuckle-walk. But I've seen them using their knuckles for leaning on while walking, and even using true knuckle-walking a bit.
This is a siamang:
http://img169.imageshack.us/img169/1498/siamangab2.jpg
Refer to the website address, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1698033/pdf/12952654.pdf, pertaining to the advantages of hair loss. However, there are more reasons that the hair loss among human beings could not bring about the advantages of human beings and this brings the query about why there have to be hair loss among animals and in turn, the query about the reliability of evolution:
a)It is mentioned in this website that humans evolved hairlessness to reduce parasite loads, especially ectoparasites that may carry disease. This might seem to be true at a glance. However, this could not be true on our heads since the hair on our heads could keep on growing and this would lead to ultimate parasite loads if it were uncut for more than 30 years. The total mass of the hair that a person would keep for 30 years would be a number of times heavier than the hair that has grown up in apesâ body. The only thing that causes human beings to differ from apes is the hair among the apes has been distributed over their bodies and yet human beingsâ hair is concentrated on their heads. When we compare the hair from human beings and apes, human beings could be parasite loads, whether in length or in mass, when the hair was uncut for more than 30 years. Thus, the hair among human beings could not reduce parasite loads. Instead, it might turn up to be the other way round to increase parasite loads on the condition that human beings did not cut their hair for more than 30 years. Thus, the hair loss among human beings and to cause it to grow continuously over the head might increase parasite loads and causes a disadvantage to human beings if their hair were uncut for more than 30 years. The over-concentration of hair growth on heads would not show any advantage in the long run since it would increase parasite loads.
b)It is mentioned in the website address above that hairlessness is made possible in humans owing to their unique abilities to regulate their environment via fire, shelter and clothing. Refer to the website address, http://en.wikipedia.org/wiki/Androgenic_hair, it shows the distribution of hair among men and women. Despite human beings might put on clothing, yet the hair among human bodies especially those parts that are covered by clothing would not reduce. This gives the implication that our hair might not be able to reduce in spite of our capabilities to regulate environment via fire, shelter and clothing. Or else, men and women should not have hair on those parts that have been covered by clothing.
c)It is also mentioned in this website that hairlessness, then, demands some sort of explanation in evolutionary terms, and especially so as, in humans at least, hairlessness is not without its costs. Humans are more exposed to the sun, may suffer greater heat loss when the ambient temperature is low (Newman 1970; Amaral 1996) and, with the exception of the naked molerats, differ from the other hairless mammals in not having a thick or toughened hide for protection.
d)Many people in this world might have encountered hair loss problem that leads to the ultimate bald heads to annoy them and causes them to have no choice but to seek help from clinic, hair salon and etc. Yet this hair loss problem persists from generation to generation. As hair loss could cause problem among human beings and yet it persists, it places the query about the reliability of evolution. This is due to why there should be hair loss that would result in bald heads among human beings and this could not occur among apes or other animals.
e)Human beingsâ hair loss brings about the disadvantage of causing them to turn up to be gray or white at old age and this might be in concern by the old folks. Yet the situation could not change unless dye hair. However, this disadvantage of turning into gray or white hair could not occur among other animals especially apes. Or in other words, there is a disadvantage of hair loss among human beings as a result of gray or white hair in old age and this places the reliability of evolution into question.
f) It is mentioned in this website that Wheeler (1992) acknowledges that naked skin increases the rates of both energy gain and loss during periods of too much or too little heat, respectively. This might mean that naked skin is actually a worse solution when the entire day is taken into account: more heat must be dissipated from daytime exposure and, at night time, more heat is lost (Amaral 1996). 3. There is certainly a disadvantage of hair loss here due to rapid energy gain and loss as a result of hairless condition of our bodies.
Despite of our hair loss, the redundancy of hair in length, such as underneath the armpit and even from the front body onwards up to the legs, remains there without removing away or evolve away, brings a query about the reliability of evolution since what it tends not to be used and yet it still retains instead of vanishing away.
It is also mentioned in the website that humans are not literally hairless, having about the density of hair follicles expected of an ape of our body size (Schwartz & Rosenblum 1981). What distinguishes human body hair is that it is very fine and short, making it, effectively, invisible. we use âhairlessâ with respect to humans, then, to mean that they lack a dense layer of thick fur. However, this could not be true to the hair that is on our heads that could grow exceedingly and could even cause parasite loads on our head if this has been uncut for 30 or more years. Indeed, the hair on the human beingsâ heads is the longest among all animals.
It is also mentioned in this website that hair loss could be meant to promote cooling of the body. However, many men might have exposed half nakedness of their upper bodies and yet could not feel cool on their bodies and seek help from fans or air-conditioning system or breeze or etc. even at the absence of sun especially early in the morning or at night. Some people might even suffer from high fever and need to seek help from doctor despite hairless bodies could cool it down. All these have placed the query whether hairless bodies could really cause their bodies to be in cool.
From the above analyses, there places a query why there should be hair drop and it seems to have adverse effect of evolution and that places the reliability of evolution into question
http://youtu.be/Ckfrn5-86xU
Discuss. :)
Yup, the video makes a good point.